Vehicle exhaust control equipment

ABSTRACT

A casing is divided into a plurality of small parallel catalyst chambers into which are packed mesh-like catalysts whose carriers are fabrics woven from glass fibers.

United States Patent [191 Nakamura 1111" 3,811,845 1451 May 21, 1974 1 1VEHICLE EXHAUST CONTROL EQUIPMENT [75] Inventor:HarutokiNakamura,Toyonaka,

Japan [73] Assignee: Matsushita Electric Industrial Co.,

Ltd., Osaka, Japan [22] Filed: July 19, 1971 [21] Appl. N0.: 163,939

[30] Foreign Application Priority Data 3,134,457 5/1964 Marcellus55/010. 30

3,189,563 6/1965 Havel 23/288 R 3,495,950 2/1970 Barber et a1 23/288 F3,380,810 4/1968 Hamhlin 23/288 F 3,385,915 5/1968 Hamling 264/52,674,521 4/1954 Houdry 23/288 R 3,154,388 10/1964 Purse 23/288 FFOREIGN PATENTS OR APPLICATIONS 631,368 6/1936 Germany 23/288 F1,443,886 5/1966 France 23/288 F Primary Examiner-James H. Tayman, Jr.Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher 57 ABSTRACT Acasing is divided into a plurality of small parallel catalyst chambersinto which are packed mesh-like catalysts whose carriers are fabricswoven from glass fibers.

1 Claim, 10 Drawing Figures JIIIIII 111/1 1 11 LII/Ill II I1PAIENTEBmzuw v I 181L845.

'SHEEIIBFS PRIOR ART PRIOR ART F/G. 3a

- PRIOR ART FIG. 3b

VEHICLE EXHAUSTCONTROL EQUIPMENT BACKGROUND OF THE INVENTION The presentinvention relates to generally an atmospheric pollution controlequipment and more particularly a vehicle exhaust control equipment.

One of the objects of the present invention is to provide an improvedvehicle exhaust control equipment of the type using the catalysts toconvert the pollutants such as. carbon monoxide, unburnt hydrocabons andnitrogen oxides in the exhaust gases from an automobile engine intoharmless gases.

Another object of the present invention is to provide an improvedvehicle exhaust control equipment which is very effective in eliminatingthe pollutants in the exhaust gases for the purpose of atmosphericpollution control.

Another objectof the presentinvention is to provide an improved vehicleexhaust control equipment which may effectively dissipate the heatproduced in the catalytic oxidations so that the'thermal breakdowns ofthe catalysts may be prevented and the long service life of theequipment may be ensured.

Another object of the present invention is to provide an improvedvehicleexhaust control equipment which may be manufactured in a simple mannerat less cost.

SUMMARY OF THE INVENTION increase silica contents.

According another feature of the present invention, the small catalystchambers are of box-shaped and disposed on both sides of an exhaust gasintroduction passage connected to an inlet of the casing.

According to another feature of the present invention, the equipment hasa cylindricalcasing which is di-* vided into more than two smallcatalyst chambers by a plurality of doughnut-shaped partition walls, andthe mesh-like catalystsare wound around the exhaust gas introductionpassage.

According to another feature of the present invention, the last of theplurality of partition disks has no center aperture so as 'to close theexhaust gas introduction passage, and the last chamber defined betweenthis last partition disk and the side wall on the side of the dischargeend ofthe cylinder is not packed with the mesh-like catalysts and isused as a chamber for discharging the exhaust gases, which have beenmade in contact with the mesh-like catalysts, into a discharge pipeconnected to a muffler or the like.

According to another feature of the present invention, the exhaust gasintroduction passage is gradually reduced in cross. section toward thedischarge end of the casing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a block diagram of a systemfor cleaning or purifying the exhaust gases from an automobile engine;

FIG. 2 is a diagrammatic sectional view of the prior art vehicle exhaustcontrol equipment designated by 2 in FIG. 1;

FIG. 3a is a diagrammatic longitudinal sectional view of another priortype vehicle exhaust control equipment;

FIG. 3b is a cross sectional view thereof;

FIG. 4a is a diagrammatic longitudinal sectional view of a firstembodiment of the present invention;

FIG. 4b is a perspective view thereof with a top cover removed;

FIG. 5 is a diagrammatic longitudinal sectional view of a second andfourth embodiments of the present invention;

FIG. 6 is a diagrammatic longitudinal view of a third and fifthembodiments of the present invention;

FIG. 7a is a diagrammatic longitudinal sectional view ofa sixthembodiment of the present invention; and

FIG. 7b is a perspective view thereof with a part of the casing wallbeing broken away.

DESCRIPTIONDF THE PREFFERD EMBODIMENTS In FIG. 1 is shown in blockdiagram the prior art vehicle exhaust control equipment for eliminatingor purifying the pollutants included in the vehicle exhaust gases. Theexhaust gases from an automobile engine 1 is introduced through anexhaust pipe into an exhaust control equipment 2, where the exhaustgases are purified. The purified gases are introduced into a muffler 3where the sound of the gases is attenuated and the temperature of thegases is reduced, andthe exhaust gases are finally discharged into thesurrounding atmosphere through an exhaust pipe 4.

In FIG. 2 is shown in section the exhaust control equipment 2 comprisinga box-shaped casing 15 with a volume of 4 5 liters and a connecting pipe11 connected to the manifold of the automobile engine and a connectingpipe 12 connected to the muffler. A pair of spaced-apart perforatedmetal plates or screens 14 are disposed in the casing 15 to define aspace of one or two liters in which the catalysts are packed.

The catalysts generally comprise the very porous carriers consisting ofthe particles of alumina, silica or magnesia which are sintered atelevated temperatures and coated or mixed with platinum and the metaloxides such as copper, nickel, manganese, cobalt and iron oxides.However, recently it has been found out that the newly developed glassfiber catalysts are more effective to purify the exhaust gases. Thecarriers of these catalysts comprise the mesh fabrics of glass fibers orglass fiber fabrics (to be referred to as heat-resisting glass fiberfabrics hereinafter) of the type in which all of alkalines in glassfibers are eliminated by dipping these glass fibers in a strong acidbath whereby they may become rich with silica and may be rendered heatresistive with an increased activated surface area. To these carriers isapplied platinum or the above described metal oxides. Therefore theproblem is now how to provide an effective exhaust control equipmentwith the use of these mesh fabrics of glass fibers or heat-resistingglass fibers.

One arrangement of the priorart exhaust control equipment is illustratedin FIGS. 3a and 3b. Within a cylindrical casing 31 having a feed pipe 32and a discharge pipe 33 is disposed a perforated pipe 34 with aperforated area being 20-50 percent of the total surface area. One endof the perforated pipe 34 is connected to the feed pipe 32 while theother end is closed by a plug or the like. The mesh-fabric typecatalysts 35 of the type described above are wound around the perforatedpipe 34 coaxially thereof. The weight of these catalysts is about400-800 grams. The exhaust gases fed through the feed pipe 32 into theperforated pipe 34 are discharged through the perforations thereof, madeinto contact with the catalysts 35 and discharged into the dischargepipe 33.

The inventors made extensive studies and experiments in order to makefull use of the catalysts in the reactions within the casing and also toprevent the temperature of the catalysts from being elevated by the heatdissipated from the exhaust gases, and succeeded in providing anexcellent vehicle exhaust control equipment as will be describedhereinafter with reference to FIGS. 4-7.

A first embodiment is shown in FIG. 4. Within a boxshaped casing 43 aredisposed in parallel a plurality of small-sized chambers or units of themesh-fabric type catalysts 47 of the type described, the adjacentcatalyst units 47 being separated from each other by means of partitionwalls 44. These catalyst units 47 are sandwiched between a pair ofperforated metal plates or wire screens 48 and 49. The axis of each ofthe rolled catalyst units 47 may be in parallel with the direction ofthe flow of the exhausted gases or the axis of the rolled catalyst unit47 may be perpendicular to the direction of the exhaust gas flow so thatthe outer surface of the rolled catalyst unit 47 may be perpendicular tothe axis of the passage 45. A number of the rolled catalyst units 47 isdependent upon the types of automotive engines, and is preferably 28.

A second embodiment of the present invention is shown in FIG. 5. Aplurality of rolled catalysts units 58 similar to those 47 in the firstembodiment described by reference to FIG. 4 are disposed in parallel oneach side of an exhaust gas introduction passage 56 in communicationwith a feed pipe 51 of a box-shaped casing 53. The exhaust gases whichhave made contact with the catalysts 58 are discharged through theexhaust gas passages 57 into the discharge pipes-52 and 52 which areconnected to a single pipe connectedto a muffler. As in the case of thefirst embodiment, the catalyst units 58 are sandwiched by a pair ofperforated metal plates or wire screens 54 and 55 and are separated fromeach other by partition walls 59.

A third embodiment shown in FIG. 6 is similar to the second embodimentdescribed above by reference to FIG. except that the cross sectionalarea of the central exhaust gas passage is gradually reduced from a feedpipe 61 toward the rear side of a box-shaped casing 63 on the side ofits discharge pipes 62 and 62 which are also connected to a single pipeconnected to a muffler. The catalyst units 67 are also sandwitchedbetween the perforated metal plates or wire screens 64 and 65 and areseparated from each other by the partition walls 68.

A fourth embodiment of the present invention will be described byreference to FIG. 5 because its longitudinal sectional view issubstantially similar to that of the second embodiment. Whereas thesecond embodiment has the box-shaped casing, the fourth embodiment has acylindrical casing 53 about 230 mm in diameter, and

4 the mesh fabric type catalysts 58 of the type described above arewound around a perforated pipe 54 within the casing 53 connected to thefeed pipe 51. The exhausted gases are discharged into the dischargepipes 52 and 52' from the cylindrical casing 53.

A fifth embodiment of the present invention will be described byreference to FIG. 6 because its longitudinal sectional view issubstantially similar to that of the third embodiment. Whereas the thirdembodiment has a box-shaped casing, the fifth embodiment has acylindrical casing 63. The diameter of the passage is gradually reducedas in the case of the third embodiment. Each catalyst unit 67 and eachpartition wall are both in the form of a doughnut. In the third andfifth embodiments, the space of the catalyst unit is increased as itapproaches toward the discharge end of the casing, but the purpose ofthe gradually reduced-diameter passage at the center of the casing is toprevent the exhaust gases deflected at the rear end of the passage fromentering in large quantity into the last catalyst unit or units ascompared with the exhaust gases which enter into the preceding units.Therefore the density of the catalysts in the last unit or units ispreferably reduced. In the third embodiment where 12 catalyst units aredisposed, the ratio of the weight of the catalysts in the first unit tothat of the last unit is preferably 1.45:1 while in the fifth embodimentwhere six disk-shaped catalyst units are disposed, the ratio ispreferably 1.35:].

In Table 1 below, the number of catalyst units and the weight of thecatalysts in the first, second, third, fourth and fifth embodiments areshown.

Next a sixth embodiment of the present invention will be described byreference to FIGS. 70 and 7b. A cylindrical casing 73 has a feed pipe 71and a discharge pipe 72, and mesh-fabric type catalysts 77 of the typedescribed above are wound around a perforated pipe 78 in the casing 73and are separated from each other by partition disks 70. It should benoted that the last partition disk 74 closes the perforated pipe 78 sothat the exhausted gases will be prevented from directly passing intothe discharge pipe 72 without passing through the catalyst units 77.Another perforated pipe 75' is disposed between the last partition disk74 and the discharge pipe 72 so that the exhaust gases which passedthrough the catalyst units 77 may enter into the perforated pipe 75before they are discharged into the discharge pipe 72. The weight of thecatalysts in each unit is grams so that the total weight of thecatalysts in four units is 480 grams. The exhaust gases introduced intothe perforated pipe 78 through the feed pipe 71 are made to pass throughthe catalyst units 77 and then discharged into a muffler through theperforated pipe 75 and the discharge pipe 72.

In the above embodiments, an air pump or air blower has not beendescribed which is driven by the automobile engine or the battery tofeed the air into the exhaust control equipment in order to oxide CO, HCand the like in the exhaust gases which are not completely burnt in theengine, because such an air pump or blower is well known in the art andis required not only 2. By use of the partition walls or disks, theuniform temperature rise in the equipment may be attained. Furthermore,the temperature rise may be minimized. The reason is that the partitionwalls or disks are made in the vehicle exhaust gas control equipment ofthe 5 of metal and are placed adjacent to the heating catapresentinvention but also in other prior art equiplysts so that the heatdissipation by the metal partition ments. Although not specificallystated in the specificawalls or disks may be much enhanced and theabnormal tion, it is clear to those skilled in the art to provide atemperature rise of the catalysts may be prevented. double-wall casingand place heat insulating materials Therefore the local thermalbreakdowns of the catabetween the walls or to apply them on the outersurface 10 lysts may be effectively prevented. of the casing because theactivity of the catalysts is gen- 3. The temperature'rise may be furtherreduced in case erally highly dependent upon a temperature and the deofthe first, second and third embodiments because the sired temperaturemust be maintained within the cascasings are made in direct contact withthe catalysts. ing. it is of course also obviousto those skilled in the4. In the third and fifth embodiment, the exhaust gas art to provide,depending upon the characteristics of passage is gradually reduced indiameter from the feedthe catalysts used, heat dissipating means whenthe exing end toward the discharge end so that the volumes haust controlequipment is used under some special e of the exhaust gases introducedinto individual catalyst vironmental conditions or when the heatresistivity of units or chambers may be uniformly distributed. Therethecatalysts is low. fore the temperature rises in the catalyst units maybe The following advantages ar accrued fr th pr made uniform and thelocal thermal breakdowns of the ent invention: catalysts may beeffectively prevented. l. A plurality of small-sized catalyst units aredisposed the f Y fifth and SiXth embodiment, h y in parallel so that thecleaning or purification effect e g are p y so that the fabrleatleh maymay be much improved as compared with the prior art be mphfied at esscost. exhaust eohtro] equipment In which the catalysts of the Theadvantages of the present invention will become e Welght are PhleecI ehepesltloht Thls advahtage more apparent from the data given in Table 11below. become e PP y e the Space e y The data were obtained by agasoline-engine automoused for explahetleh: That In e of the Platlhumbile which were fitted with the vehicle exhaust control catalysts 10grams Weight 'h e by t heatequipments of the first to sixth embodimentsof the inl'eslshhg glass fibers the p e t y 15 times h vention duringthe travel of about 500 kilometers. The of the Catalysts 100 grathswelghtused e Prior displacement of the engine was 1,500 cc. For the sameart exhaust Centre] qt p Furthermore It was of comparison, the data ofthe vehicle exhaust control found out that the cleaning efficiency ismuch lowered equipment f the type. Shown in FIG 3 with 1,400 the Priorart exhaust Control q fp Where h grams of the mesh-fabric typeheat-resisting-glass-fiberchtalysts more 500 gf Wetght are P carriercatalysts are shown also in Table II. The cataone space as compared withthe exhaust control equ1plysts used are as f ll mentof thepresentmventlon in wh ch these catalystS Carriers: mesh-fabrics ofheat-resisting glass fibers are l "h uhlts each cohtammg 60400 gramsCatalysts: metal oxides whose major portions are coahd dlsposed patahetother words, y the Pttmhel 4O balt oxides and copper oxides and whichcontain as arrangement of the small-sized catalyst units, the cleaauxiliary catalysts small quantities of chromium oxing or purificationeffect may be much improved while ides, aluminum oxides, magnesiumOxides and the exhaust control equipment may be made compact phosphorusin size.

Table ll idhl g after 500 km travel I average CO average weight ofpurifi- CO in '71 CO in 7: temperature catalysts cation at at ofcatalysts in grams rate in 7:- inlct outlet in "C comparison (See Fro.31

1,400 68 1.2 0.6 680 first embo- 720 92 1.4 0.3 540 diment second embo-600 94 1.5 0.2 570 diment third embos00 94 1,7 0.3 490 diment fourthembo- 540 93 0.x 0.15 610 dimcnt fifth embo- 540 1.0 0.2 630 dimentsixth embodiment In all of the embodiments described above, the numbersof small-sized catalyst units or chambers as well as the weights andtypes of the catalysts used are specified, but it is understood that thearrangements of more than two small-sized catalyst units or chambers inparallel are within the scope of the present invention. It is alsounderstood that the types and weights of the catalysts are of courseselected depending upon the types of the automobiles and that thecatalysts may be of the type in which platinum or metal oxides areapplied as the catalyst layers upon the surfaces of the fabrics wovenfrom the heat-resisting glass fibers. It is also understood that thegradual reduction in diameter of the perforated pipe 78 in the sixthembodiment is also within the scope of the present invention.

The vehicle exhaust control equipment in accordance with the presentinvention may be fabricated at less cost and has an excellent exhaustgas cleaning or purification effect, and is very effective as ananti-atmospheric-pollution control equipment.

What is claimed is:

l. A vehicle exhaust control device capable of dissipating the heatproduced during catalytic oxidation of exhaust gases without thermalbreakdown comprising in combination an outer casing having gaseous feedmeans and discharge means,

an exhaust gas introduction passage within the interior of said casingin communication with said gaseous feed means comprising a centralperforated pipe,

a plurality of heat conducting annular partitions having a diameter lessthan the diameter of said outer casing positioned around said perforatedpipe which are not permeable to the gas and which divide portions of theinterior of said outer casing into a plurality of small catalystchambers which are arranged parallel to the flow of exhaust gas throughsaid exhaust gas introduction passage and forming a continuous gasannular passage between said catalyst chambers and said outer casing,

woven meshlike catalysts positioned within said small catalyst chambersand wound around said perforated pipe to form separate catalyst elementscontiguous with said heat conducting partitions, whereby said catalystelements are maintained in said chamber free of perforated retainingmembers, and

at least one of said partitions blocking the downstream end of saidexhaust gas introduction passage to cause the exhaust gas to passthrough said small catalyst chambers containing said woven meshlikecatalysts and into said continuous gas annular passage,

whereby the heat produced in the catalytic oxidation is effectivelydissipated to prevent thermal breakdown of the catalyst.

